New SCAAR Scare? Restenosis Rates Double in Diabetics With Endeavor Stent

Shelley Wood

September 02, 2008

September 2, 2008 (Munich, Germany) — Nearly two years after Swedish investigators shocked the cardiology community with registry data hinting that drug-eluting stents (DES) might increase death rates by 30% after six months, the Swedes are back with new data showing that the Endeavor stent is associated with more than twice the risk of restenosis in diabetics than the Cypher or Taxus stents.

The new data were presented here at the European Society of Cardiology Congress 2008.

According to Dr Bo Lagerqvist (Akademiska University Hospital, Uppsala, Sweden) the SCAAR registry data support calls for larger comparative DES trials, particularly in diabetic patients.

"In this large real-world registry, there were large differences in restenosis rates between different types of DES with and without diabetes," he said. "This reinforces the need for larger, randomized prospective trials with head-to-head comparisons between the different stent types, both in diabetics and nondiabetics."

Due to the nature of the nationwide registry, Lagerqvist et al's study looked specifically at restenosis on a per-stent (not per-patient) basis, making it impossible to compare the results with rates of other events like death or MI for the entire data set. But in a separate analysis that considered patients who had just one stent each, the risk of death and the risk of MI were no different between the different stent types, both for the entire SCAAR population and in separate analyses of diabetic and nondiabetic patients, Lagerqvist stated.

SCAAR Can Still Scare

This latest analysis looked only at stent brands that have been implanted at least 500 times since December 31, 2007, thus including the Cypher, the Taxus Express, the Taxus Liberté, and the Endeavor (the Xience did not meet the 500-stent cutoff). During this time period, 35 478 stents were used, of which 23.2% were used in diabetics. The Cypher was the most commonly used stent in diabetic patients, at 2616, followed by the Taxus Liberté (2553), the Taxus Express (2182), and the Endeavor (881).

Out to three years of follow-up, there were no significant differences in restenosis rates between the two Taxus stents and the Cypher in diabetic patients, even after adjustment for confounding factors. But when the Endeavor stents were added to the analysis, the relative risk of restenosis for diabetics was twice as high in the Endeavor as it was with the other stents. A similar analysis conducted in nondiabetic patients also pointed to higher rates of restenosis for the Endeavor, but not to the same degree.

Relative Risk of Restenosis for Endeavor

Comparison Relative Risk 95% CI
--Endeavor vs Taxus Liberté 2.18 1.55–3.07
--Endeavor vs Taxus Express 2.08 1.43–3.00
--Endeavor vs Cypher 1.99 1.43–2.77
--Endeavor vs Taxus Liberté 1.31 1.03–1.67
--Endeavor vs Taxus Express * *
--Endeavor vs Cypher 1.23 0.97–1.55

size="1">*Not presented

In an intriguing, albeit unrelated, observation, restenosis rates were also 32% higher for the Taxus Express than for the Taxus Liberté and 24% higher for the Taxus Express vs the Cypher.

"The influence of diabetes on restenosis risk differs with type of DES," Lagerqvist concluded. "In patients with diabetes, the risk of restenosis is doubled in lesions stented with Endeavor compared with lesions stented with Cypher or Taxus stents."

What About Hard Events?

To heartwire , Lagerqvist emphasized that the mortality analysis provides some comfort. "Of course, these data are meaningful for those patients who have to come back and have a second procedure, but the most important question is of course mortality, and we can't really see any differences in our registry."

Dr Franz R Eberli (University Hospital Zurich, Switzerland), who chaired the session, told heartwire that he was "not at all surprised" by the SCAAR data, particularly since preapproval studies consistently pointed to higher late loss with this stent.

"Even from clinical experience, you know that the Endeavor stents have more restenosis than Taxus or Cypher. Even the [ENDEAVOR III] trial of Cypher vs Endeavor in all-comers was negative; the Endeavor didn't meet the test for noninferiority, meaning that it was inferior."

And there are "many reasons" why this difference would be more pronounced in diabetics, he added. "There may be a different pattern of using this," Eberli explained. "Endeavor is much easier to deliver, so inexperienced operators may be using it more often. This could be a confounder. And diabetic patients have smaller vessels, more calcifications, so it's harder to deliver the stent. Many people will say, okay, I have to get a stent down there; I don't care if the patient comes back a second time for another stent, it doesn't affect mortality."

That said, Eberli is not completely reassured by the mortality analysis Lagerqvist presented.

"There's a very nice study showing that in diabetic patients, patients who restenosis have a higher mortality, so higher restenosis rates with Endeavor could well effect mortality, especially if you look at multiple lesions and the more seriously diseased vessels. Some of these patients will have totally occluded vessels and will have to go to CABG surgery, so it could still have effects on mortality. But you would need 1000 patients or more to see a difference; this analysis included just 800 Endeavor stents."

While news of fresh SCAAR data will likely send shivers down the spines of interventionalists and market-watchers alike, many will remember that, at least in the case of the original SCAAR scare, time will tell. DES use had plunged from 60% to 15% in Sweden by the time late follow-up of the original DES-vs-bare-metal-stent data suggested that the mortality risk for DES was no different from that of bare-metal stents at four years.

Lagerqvist declared having no conflicts of interest.

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